Battery packs are used with the Cardiosave Hybrid/Rescue Intra-Aortic Balloon Pump to inflate and deflate intra-aortic balloons that support the left ventricle. The packs are relied on when AC power is not available.

http://www.fda.gov/medical-devices/medical-device-recalls/datascopegetingemaquet-recalls-cardiosave-hybridrescue-intra-aortic-balloon-pump-battery-packs-due